Taking out a loan is one of the necessary evils of life, the knowledge that paying it back is going to make balancing your checkbook a nightmare. Not all of us are born math wizards, and figuring out how much we owe per month keeps a good number of us up long past our bedtime. However, at the risk of sounding cliched, there really is an app for that. In fact, there are hundreds; some great, some not. Here are the three best loan calculator apps.

1. Simple Loan Calculator

Doing precisely what it says on the label, the Simple Loan Calculator will help you plan out your fixed, differentiated and annuity payments. You can see the monthly payment, the interest paid, and the credit total across a number of different loans. The app also provides charts, letting you graphically track your payment progress. User reviews indicate that the Simple Loan Calculator is quick, straightforward and very user-intuitive. It’s free, and, best of all, open source, meaning that improvements to the app can be fluid, fast and constant, and not locked into a development cycle.

2. Loan Calculator Pro

SVT Software promises that you can make monthly payment calculations within seconds using their Loan Calculator Pro app. Whether it’s your house, your car or your credit card, you can even calculate hypothetical situations to estimate paying off your loan sooner than you anticipate, and save interest money. You can track extra payments of variable amounts for the remaining life of the loan, perform calculations instantly (thanks to the software), see the amount, principal, interest, and remaining balance for every single loan payment, and even e-mail your bookmarks, charts and payment history. The app also offers an extra-large keyboard, for easy and accurate data entry.

3. Loan Calculator – What If?

Imagine if you could calculate monthly payments for any fixed rate loan, or for your house, your credit card, your car with just a couple of clicks. That’s what Loan Calculator – What If? offers. You can plot out your monthly or yearly payments, and see how best you can save potentially thousands of dollars in interest. The app also gives you an amortization schedule, so you can see how much of the principle on the loan will be paid off every month. The simple interface, customer satisfaction, stripped-down input and output features and e-mail functionality